From: Li Zefan Date: Fri, 25 Jan 2013 08:08:01 +0000 (+0800) Subject: cpuset: fix cpuset_print_task_mems_allowed() vs rename() race X-Git-Tag: v3.4.35~12 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a74e9a386f6e775f88061f7958b8b34c6742f926;p=karo-tx-linux.git cpuset: fix cpuset_print_task_mems_allowed() vs rename() race commit 63f43f55c9bbc14f76b582644019b8a07dc8219a upstream. rename() will change dentry->d_name. The result of this race can be worse than seeing partially rewritten name, but we might access a stale pointer because rename() will re-allocate memory to hold a longer name. It's safe in the protection of dentry->d_lock. v2: check NULL dentry before acquiring dentry lock. Signed-off-by: Li Zefan Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 5fc1570e64c1..8fe6f6b65006 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2479,8 +2479,16 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk) dentry = task_cs(tsk)->css.cgroup->dentry; spin_lock(&cpuset_buffer_lock); - snprintf(cpuset_name, CPUSET_NAME_LEN, - dentry ? (const char *)dentry->d_name.name : "/"); + + if (!dentry) { + strcpy(cpuset_name, "/"); + } else { + spin_lock(&dentry->d_lock); + strlcpy(cpuset_name, (const char *)dentry->d_name.name, + CPUSET_NAME_LEN); + spin_unlock(&dentry->d_lock); + } + nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, tsk->mems_allowed); printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",